Shop Solutions: Punch Grinding on a Grand Scale

Punch grinding may seem like a niche grinding application, and it probably is. Which is not to say there are not many players--there are. Just check out any fabricating or forming magazine. But how many of them supply punches for nearly every machine builder? And how many sell aggressively into the global market? Call it a niche, but from where Exacta Precision Products Ltd. (Scarborough, ON, Canada), sits, it's a pretty big niche.

"Price, quality, and delivery are all on an equal footing today," says Noubar Korkorian, plant manager for Exacta. "But delivery becomes very important, especially if you're selling into the global market. In any case, if you miss a delivery, you lose a customer. It's that simple."

Exacta was formed in 1967 to manufacture punches and dies for the metal-fabrication industry. It grew from a small space in an industrial plaza to a modern 40,000 ft2 (3716 m2) manufacturing facility with satellite operations in Montreal and Nashville, TN. Industries served by Exacta include automotive and general metal fabrication. The company employs some 180 worldwide, with 140 at the Scarborough site, and maintains an arsenal of manufacturing equipment, including two Studer S32 punch grinders from United Grinding Technologies (Miamisburg, OH).

Typical punches are from 0.025 to approximately 4.500" (0.64 - 114-mm) cutting diam. Exactas can grind any outside profile that they can generate, and that a customer may require. Exacta manufactures tooling for 27 different lines, each line consisting of a different manufacturer of fabricating equipment.

Korkorian explains that one of the keys to Exacta's success lies in a well-stocked inventory, which at first glance may seem to run contrary to today's lean-manufacturing philosophy of holding as little inventory as possible. In Exacta's case, however, having inventory depth is crucial to meeting the demands of all those lines, as well as competing globally. Korkorian says that the company buys its raw bar stock, does all the required CNC machining, secondary operations, milling, turning, and then heat treating. After heat treat, they grind the blanks to size and put them in stock. As the orders come in, they pull from stock and finish the specified point, shape, or profile.

As important as inventory depth and production flexibility are to Exacta, Korkorian says the real competitive edge is technology. "If we didn't have the technology we have today," he says, "we wouldn't be competitive."

Korkorian speaks specifically about the two Studer S32 punch grinders. "After we first heard about Studer, UGT came in and gave us a demonstration. We spoke to others who had an S32, and the technology impressed us. We wanted to go to the superabrasive wheel, because we feel that's the future." The company has six cam grinders and three CNC servocontrolled cam disk grinders.

"But since we got the Studers," Korkorian says, "we've reduced our production time by half. And because of the superabrasive wheel, we have reduced downtime tremendously."

He notes that when Exacta used a regular CNC punch grinder with aluminum oxide wheels, they'd change the wheel every three days. "Every three days, we'd have downtime of 45 min," says Korkorian. "With the Studer, one wheel lasts about seven months. That means we've reduced our downtime by 34 hr. In that 34 hr I can grind many extra punches."

Korkorian also says that due to the S32's special coolant tank with magnetic separator, coolant is kept clean at all times. With other machines, they'd normally have to clean the coolant every three weeks, a process that consumes 1 1/2 hr.

And then there is changing the diamond. "With the previous machines, every time we'd change a wheel, we'd change the diamond," Korkorian says. "With the Studer, we don't change the diamond. The Kaiser has been on the machine since we bought it--seven months ago. So if previously a diamond lasted us a week, you're looking at changing 28 diamonds in that seven-month period."

He also notes that with the previous machines, they'd have to dress the wheel 0.0050" (0.127 mm) at every dress; with the Studer, they take about 0.0004" (0.010 mm) each day, and with continuous dressing they don't lose downtime--i.e. production--dressing the wheel.

Korkorian says that the Studers have allowed them to tackle jobs more efficiently than they could with their previous equipment. If they've got a punch with a profile that's about 4" (102-mm) long. They set the part up on the Studer, center it, and grind. But not in the usual fashion. They step-grind the part.

"You see," he says, "the wheel on the Studer is 1.50" [38-mm] wide. The profile is 4". So what we do is plunge, move over, plunge, move over--until we've ground the full profile length. Then the machine is programmed to oscillate, blending the grinding out so that the surface finish is very fine and smooth. We couldn't do this successfully prior to the Studer."

Once you program a job, Korkorian says, the control stores all the information about that job--speeds, feeds, profiles, angles, materials--in a library. When you want to run a job, you call it up. If you've got a new job that's similar to another, you call up the stored job and edit it, and then store the new job.

Long runs, generally for stock inventory, are run at the same time as short runs. If the need arises, a long run can be interrupted for a rush job, and then put back on the S32 when the rush job is done.

Korkorian notes that the value of the Canadian dollar influences his global competitiveness. If the Canadian dollar strengthens against other currencies, that will have a negative impact. But, Korkorian notes, currency fluctuations are just that: fluctuations. Currencies rise, dip, and rise again. They're not predictable in the long term.

What is predictable, Korkorian says, is that using the best technology and a sound manufacturing strategy give Exacta a sizeable competitive advantage, regardless of currency fluctuations. "We know what we can control," Korkorian says. "Namely our production methods and processes, and the technology investments we've made. It's this, and our employees, not the value of a currency, that have kept us growing every year since we were founded."

Press Produces Laminate Components

Boeing Canada Technology (Winnipeg, Manitoba, Canada) is an important composite manufacturing center for The Boeing Company (Chicago), and the applied technology they develop is used to expand the horizons of worldwide flight. They have teamed up with the Beckwood Press Company (St. Louis, MO) to develop a customized press to reduce costs for their current product, and develop new parts for Boeing's cutting-edge passenger-plane technology.

Opening in 1971, Boeing Winnipeg began with 50 employees at their facility, and has grown to be the largest aerospace-composite manufacturer in Canada. The company has expanded to 940 employees with a manufacturing plant that covers roughly 600,000 ft2 (55,740 m2). Boeing Winnipeg designs, develops, and fabricates complex composite structures and subassemblies for aerospace customers. They specialize in wing-to-body fairings, engine strut fairings, thrust reverser blocker doors, as well as additional complex composites including nacelle chines, landing gear doors, and high-performance ducts.

The Boeing Company constantly develops new technologies to reduce cost and weight of their products. Often, the Winnipeg Div. looks to replace components that were historically fabricated from metals, and replaces them with cutting-edge composites. In a recent application, Boeing Winnipeg needed a state-of-the-art press to manufacture reinforced thermoplastic laminate (RTL) components. This was a new technology for the plant, and they needed a hydraulic press partner to work with on the automation and integration of the production process. "The flexibility of design was extremely important as we had to integrate a specialized, Winnipeg-built, pre-heat oven with the press. We needed a company willing to work with us on the integration with a tight timeline," says Mark Shead, Boeing Engineering Specialist.

"Beckwood Press was chosen as they offered the best value and could meet our tight timelines. They were also willing to integrate the press and control system with the custom pre-heat processing oven that was being built here," says Shead.

The confluence of this relationship was a 230-ton (1023-N) capacity hydraulic press that employs an up-acting design with a precise 32 x 44" (813 x 1118-mm) heated platen. Beckwood was able to combine various engineering specifications from their experience with different types of applications to create a press with a high level of control over position and speed.

Speed is variable throughout the stroke, and the press is equipped for a variable dwell under pressure. Feedback for position and speed is controlled through independent zones with linear and pressure transducers that work with an Allen Bradley control system. Beckwood integrated the compression molding press with a pre-heat oven and shuttle mechanism that moves the workpiece seamlessly through the press. Parts are heated with tight temperature control and a precision heated platen with a maximum heating temperature of 450°F (232°C). The press was engineered with a 22" (559-mm) stroke and remote power. "The most impressive aspect of the press is its reliability. It has been in production for over a year and we have had no breakdowns," Shead observes.

The new press is being used to make Boeing 737 and 777 slat track flex tabs, but this new manufacturing process will be expanding to larger and more complex applications over time. RTL applications include flight hardware on the new 787, which will have almost 40% more composite materials than the 777. Major production of the new 787 airplane begins in 2006, first flight is scheduled for 2007, and the first delivery will be in 2008.

Software Speeds CMM Programming

Software must change to stay on top of what's best for specific machines and situations. That's where TECT (Turbine Engine Components Technologies) Corp.; (Thomasville, GA) stood when informed of pending changes in the operating format of the control software package they had been using for years. In the CMM inspection area, the extensive programming required using the old system had already become a huge problem. Instead of trying to go through a complete new learning curve for an older system that was already cumbersome, it was time to start looking for something new and easy to learn. "The goal was to find a software package that could handle all CMM programming needs off-line or on-line, for diverse machines, and do it at minimal cost with a short learning curve," explains Bill Hopkins, senior CMM manager at TECT.

TECT is a privately held company, with multiple divisions involved in the custom manufacturing of semifinished and finished components and assemblies for aerospace, power generation, rail, off-highway, automotive, and other industries. The Thomasville division manufactures fan and compressor blades and vanes for most of the major jet engine manufacturers, commercial and military.

They operate with a commitment to statistical process control (SPC), aimed at maintaining part-to-part consistency within a chosen optimum process capability. Statistical profiles are performed for various product characteristics exhibited over time using inspection equipment ranging from simple hard-point gages to computer-based gages and CMMs.

TECT runs a three-shift operation with multiple lines in operation at all times, including all final test, measurement, and inspection, which is critical to all parts. Time is at a premium, and excess time in machine programming equates to money lost.

There were two main reasons to start looking for new CMM programming software. "First," says Hopkins, "because the package being used was going to be radically changed, it was the perfect time to research the market. Also, with new projects coming on board, more exotic configurations with even tighter specifications would be required for final inspection. Software was needed that could program the CMMs for these products." Because an upgrade would be potentially complicated, time consuming, and expensive, TECT considered that they had an opportunity to see if a program could be found that would handle the new requirements with less downtime for installation and training.

TECT uses CMMs with a variety of probe technologies on the production floor for final inspection. With the current software, two engineers were dedicated to programming the CMM area, and a third was being hired because the workload had gotten so heavy. Within one new project alone, there were seven part numbers in the part family that looked alike, and yet were dimensionally different. A CMM program had to be developed for each part number for final inspection.

Aside from this new project, the plant still ran large lots of parts. "But even there," Hopkins points out, "the way we approached production was changing. Formerly, a substantial amount of customized gaging tools were purchased from outside sources and used by operators to measure parts. The movement is now more heavily toward only using CMMs for the task."

This change reduces cost, as investing in the custom gaging was very expensive, and the gages also had to be maintained. The ideal situation was to be able to generate programs on the CMMs to handle all part measurement, regardless of the customization required. For these reasons, a streamlined CMM programming area had the potential to save a lot of money in various areas, not just final inspection. Labor hours, time to create programs, time to measure parts, and financial investment in production gaging would all benefit.

Quotes were obtained from every likely supplier and comparisons were made; the candidate list was long. The final decision resulted in the selection of a CAD-based product called CMM-Manager from Integrated Quality Inc. (Lewis Center, OH). This company developed some of the programs that were included in the old software package that TECT was switching from, which was how their name got onto the initial contact list.

The major factors for the purchase of this software program were initial cost of the software, short learning curve, and fast ROI. The benefits were programming that could integrate with any type of machine without the need for special adaptation software or hardware, and the fact that the software did exactly what was needed. There was no overkill.

Programming that previously took 100 hr can now be done in less than 40.

The new software handles all needs in one package. Off-line programming saves time by allowing part-inspection programming without tying up machines on the shop floor. While on-line programming is still needed in some cases for some machines, particularly when part models aren't available, the program is easier to learn than the previous software. After three days of training, TECT engineers had written new programming that previously took two and a half weeks to write for the CMM area.

The software also creates travelers for all the parts for traceability. The CMM report was included with the part, and the software also provided an electronic copy of the report. "Another very nice feature is that if anyone in virtually any location needed to retrieve or review any report, it's viewable using an Internet web browser," says Hopkins. Graphical reports generated by the program are easy to use and informative. Previously, many of the graphical reports generated using the older program required a good deal of deciphering. Technical resources were constantly required to develop ways to try to identify exactly what characteristics were being measured, and where they were on the part. The software indicates exactly where the characteristic originated, the tolerances, and any deviations-all in one picture.

Today, writing new programs that used to take months take only weeks. Ten CMMs can be programmed offline quickly to measure and analyze all products requirements, including point cloud areas that were not possible using the previous software.

This article was first published in the November 2005 edition of Manfacturing Engineering magazine.